An organic electroluminescence device has been known as a device using a thin film (hereinafter, referred to as an organic film) that is made of an organic compound forming electroluminescence (hereinafter, referred to as an EL) by the supply of current. The organic EL device is formed by sequentially laminating, for example, transparent electrodes, one or more organic films, and metal electrodes on a transparent substrate.
An organic EL display panel that includes a plurality of organic EL devices as a light-emitting part, for example, a matrix type organic EL display panel is formed by sequentially laminating horizontal line electrodes that include a transparent electrode layer, one or more organic films, vertical row electrodes that include a metal electrode layer crossing the line electrodes. Each of the line electrodes is formed in the shape of a strip. The line electrodes are arranged parallel to each other with a predetermined distance therebetween, and the row electrodes are the same as the line electrodes. As described above, the matrix type display panel has an image display array that includes a plurality of light-emitting pixels of organic EL devices formed at junctions between the plurality of line and row electrodes.
In a process for manufacturing the organic EL display panel, the transparent electrode layer is formed on the transparent substrate, and the organic films are then formed. The organic films are one or more thin films corresponding to the light-emitting pixels, and are formed by a deposition method.
For example, when an organic film is formed on the entire surface of a substrate on which first display electrodes are patterned by a wet process, such as a spin coat method or a spray method, as one method of manufacturing the organic EL device, the organic film formed on electrode lead portions should be removed so that the electrode lead portions come in contact with the first display electrodes. For this purpose, there has been known a method of removing an organic film formed on the electrode lead portion that uses, for example, a photolithographic method, a laser abrasion method, or a method using an etching mask.
First, the photolithographic method includes applying a resist on a thin film formed on a substrate, exposing the resist, dissolving exposed portions of the resist having predetermined patterns in a developer (positive type) or not by dissolving the exposed portions (negative type) in order to form a resist mask, and etching the thin film in order to pattern the thin film into etched and un-etched portions.
In the laser abrasion method, generally, a focused laser beam is radiated onto a thin film in order to vaporize and peel the thin film, and the radiation is selectively repeated to pattern the thin film into peeled and unpeeled portions.
The method using an etching mask is a method using an etching mask where a region corresponding to an etched region of an object to be etched is opened and a region corresponding to a region not to be etched (an un-etched region) is not opened and by performing etching through the opened region. Since the etched region of the object corresponding to the opened region of the etching mask is etched and the un-etched region is not etched, the object is patterned into etched and un-etched portions. For example, a method disclosed in the following Patent Document 1 has been known as the method using an etching mask.
In general, a non-opening portion of an etching mask forms an un-etched region in order to make an un-etched region have the shape of an island surrounded by an etched region. Patent Document 1: JP-A-2004-273438